What do you know about for loop and do while loop?

Answer 1

The condition for a while loop is tested at the start of the loop. It is tested at the end of the loop for a do-while loop.

The body of a do-while loop will always be executed at least once. Whereas for

a while loop if the condition is false to start with, the body of the loop is never executed.

Answer 2

The loops are the same. The test is at the start of the loop so both are done zero or more times.

The main difference is that the for loop has a built in subscript. The while loop you have to create any subscripts that you need and also add the increment where needed.

Answer 3

In C, for loops, while loops, and do while loops are control structures for repeating a sequence of code based on a condition. While loops and for loops are interchangeable and work top down meaning it is possible to skip their code entirely. do while loops check the condition at the bottom of the loop meaning they always run their code at least once. the syntax for a for loop is as follows

for(c = 0; string[c] != NULL; c++)

{

printf("%c", string[c]);

}

this segment of code would print the elements of the character array string until an element was equivalent to NULL, the end of file character found at the end of strings.

the first statement is typically used to set a counter to keep track of how many times you have gone through the loop, either incremented as in the case above or decremented. This could be left blank but the semi colon is still needed.

The line following the first semi colon sets the condition. The condition is evaluated as a Boolean expression, and the loop will continue to run its block of code until the condition is false . The condition must be followed by a semicolon.

The statement after the second semi colon is typically used to update the counter. This likewise can be left blank but the semicolon is still needed. Any loop that does not update itself in some way will usually result in an infinite loop and unless there is something else built into the code such as a break statement this will cause a run time error. This means program would compile correctly and then crash during the run time.

A while loop could also be used to write a completely equivalent code.

c = 0;

while(string[c] != NULL)

{

printf("%c", string[c]);

c++;

}

Note that the variable being used to count through the loop is declared out side the loop. While loops consist only of a condition, and will loop through the block of code within them until the condition is false, like all loops.

the do while equivalent would look like this

c = 0;

do

{

printf("%c", string[c]);

c++;

} while( string[c] != NULL);

if string[0] was a NULL character, this code would still run once printing a NULL character to the screen before checking the condition. If the first character was not a NULL character, then this would run identically to the other loops described.

Answer 4

The difference is that do while loop allows you to make at least one iteration, even if the condition for while is wrong. For loops does not allow you to do that.